Lightweight high damping porous metal/phthalonitrile composites

Abstract

Metal foams are impregnated with a phthalonitrile prepolymer. The metal f/polymer composite formed upon curing has excellent acoustic damping, structural properties, oxidative stability, and flame resistance. Foams of various metals, such as aluminum, titanium, nickel, copper, iron, zinc, lead, silver, gold, platinum, tantalum, and alloys based on these metals may be used.

What is claimed is: 
     
       1. An acoustically damping composite comprising a metal foam, said metal foam having an open cell structure, impregnated with a cured phthalonitrile polymer. 
     
     
       2. The composite of claim 1, wherein said metal is selected from the group consisting of aluminum, aluminum base alloys, titanium, titanium base alloys, nickel, nickel base alloys, copper, copper base alloys, iron, iron base alloys, zinc, zinc base alloys, lead, lead base alloys, silver, silver base alloys, gold, gold base alloys, platinum, platinum base alloys, tantalum, and tantalum base alloys. 
     
     
       3. The composite of claim 1, wherein said metal foam is an aluminum base alloy foam. 
     
     
       4. The composite of claim 1, wherein said metal foam is a titanium foam or a titanium base alloy foam. 
     
     
       5. The composite of claim 1, wherein said metal foam is a copper foam or a copper base alloy foam. 
     
     
       6. The composite of claim 1, wherein said metal foam is a zinc foam or a zinc base alloy foam. 
     
     
       7. The composite of claim 1, wherein said cells have a locally uniform diameter. 
     
     
       8. The composite of claim 7, wherein said metal foam has a gradation of pores sizes in at least one direction along the metal foam. 
     
     
       9. The composite of claim 1, wherein said composite article is in the form of a sheet. 
     
     
       10. A laminate comprising a plurality of sheets according to claim 9 bonded together. 
     
     
       11. A composite according to claim 1, wherein said metal foam has an average pore size of about 5-100 pores/inch and a percent foam density of about 5-40. 
     
     
       12. A composite according to claim 11, wherein said metal foam has an average pore size of about 10-50 pores/inch. 
     
     
       13. A composite according to claim 1, wherein, along its smallest dimension, said metal foam is no smaller than 1.5 times the average void diameter of said pores. 
     
     
       14. A method of forming a composite comprising the steps of: impregnating a metal foam, said metal foam having an open cell structure, with a phthalonitrile resin component; and   converting said phthalonitrile resin component into a solid phthalonitrile bulk polymer within said open cell structure.   
     
     
       15. The method of claim 14, wherein said impregnating step is carried out by placing said cell under a vacuum and contacting said cells, while under vacuum, with said phthalonitrile resin component. 
     
     
       16. The method of claim 14, wherein said impregnating step is carried out by forcing, under positive pressure, said phthalonitrile resin component into said cells. 
     
     
       17. The method of claim 14, wherein said metal is selected from the group consisting of aluminum, aluminum base alloys, titanium, titanium base alloys, nickel, nickel base alloys, copper, copper base alloys, iron, iron base alloys, zinc, zinc base alloys, lead, lead base alloys, silver, silver base alloys, gold, gold base alloys, platinum, platinum base alloys, tantalum, and tantalum base alloys. 
     
     
       18. The method of claim 17, wherein said metal foam is an aluminum base alloy foam. 
     
     
       19. The method of claim 14, wherein said metal foam has a pore size of about 5-100 pores/inch and a percent foam density of about 5-40. 
     
     
       20. The method of claim 14, wherein said composite is a sheet. 
     
     
       21. A method of forming a laminate, comprising the steps of: producing a plurality of sheets according to claim 20, said sheets being the same or different;   bonding said sheets together to form a laminate.